Pump including a moving member provided with a central duct and a diaphragm having engagement means bearing against said central duct, and a receptacle fitted therewith

ABSTRACT

A pump of the type comprising a moving member mounted to move relative to a support, the moving member having a central duct in which the substance to be dispensed penetrates via at least one opening, the support co-operating with the moving member to define a variable-volume pump chamber around said central duct, the pump having a diaphragm held by retaining means on the support, the diaphragm having a central portion in which one end of said central duct is inserted, the diaphragm having a valve-forming portion arranged to isolate the pump chamber from said opening(s) of the central duct while the volume of the pump chamber is increasing and the substance is being sucked into the pump chamber, the diaphragm also bearing against the moving member in such a manner that movement of the moving member to dispense the substance causes the diaphragm to be stretched elastically. The pump has means suitable, during movement of the moving member for dispensing the substance, for minimizing the stretching of the valve-forming portion of said diaphragm.

[0001] The present invention relates to a pump and to a receptaclecontaining a liquid, e.g. a cosmetic or care cream, and fitted with sucha pump.

BACKGROUND OF THE INVENTION

[0002] French patent FR-B-2 728 809 discloses a pump having a pushbuttonmovably mounted on a support secured to the receptacle containing thesubstance to be dispensed, the pushbutton having a central duct providedwith a radial opening at its bottom end, the support defining avariable-volume pump chamber around said central duct. A diaphragm madeof elastomer material is mounted on the support. The diaphragm has acentral portion in the form of a sleeve that is open at its top end andclosed at its bottom end. The central duct of the pushbutton is insertedin the diaphragm via one end until it bears against the end wall of thecentral portion of the diaphragm.

[0003] The above diaphragm acts as a spring for returning the pushbuttonto its initial position after dispensing a quantity of substance.

[0004] It also acts as a delivery valve.

[0005] During the return movement of the pushbutton, the diaphragmpresses against the central duct and isolates the pump chamber from theradial opening in the central duct so as to prevent air returning intothe pump chamber.

[0006] Such a pump has the advantage of requiring only a small number ofparts and thus of being suitable for manufacture at relatively low cost.

[0007] Nevertheless, that known pump does not provide full satisfaction.

[0008] In particular, the pump can be difficult to prime and undercertain conditions the substance flows with difficulty between thecentral duct of the pushbutton and the diaphragm, thereby causing thepushbutton to jam.

OBJECTS AND SUMMARY OF THE INVENTION

[0009] The invention seeks to further improve a pump of the typecomprising a moving member mounted to move relative to a support, themoving member having a central duct in which the substance to bedispensed penetrates via at least one opening, the support co-operatingwith the moving member to define a variable-volume pump chamber aroundsaid central duct, the pump having a diaphragm held by retaining meanson the support, the diaphragm having a central portion in which one endof said central duct is inserted, the diaphragm having a valve-formingportion arranged to isolate the pump chamber from said opening(s) of thecentral duct while the volume of the pump chamber is increasing and thesubstance is being sucked into the pump chamber, the diaphragm alsobearing against the moving member in such a manner that movement of themoving member to dispense the substance causes the diaphragm to bestretched elastically.

[0010] The new pump of the invention has means suitable, during movementof the moving member for dispensing the substance, for minimizing thestretching of the valve-forming portion of said diaphragm. In apreferred embodiment, the central portion of the diaphragm has firstengagement means arranged to co-operate with second engagement meanssecured to the central duct, the second engagement means being spacedapart from the end of the duct which is inserted in the central portionof the diaphragm.

[0011] By the invention, the end of the central duct bears only lightlyor not at all against the end wall of the central portion of thediaphragm when the moving member is moved to dispense the substance,unlike the pump described in French patent 2 728 809 in which thediaphragm is stretched elastically, specifically by the fact that thecentral duct of the pushbutton bears directly against the end wall ofthe sleeve-shaped central portion of the diaphragm.

[0012] Advantageously, the portion of the diaphragm extending betweenthe retaining means of the support and the engagement zone of thecentral duct performs a spring function only.

[0013] Also advantageously, the portion of the valve-forming diaphragmthat is arranged to isolate the pump chamber from the opening(s) of thecentral duct lies outside the portion of the diaphragm that extendsbetween the zone for fixing on the support and the zone for engagementon the central duct.

[0014] In the invention, the central portion of the diaphragm comes tobear against the central duct at a location that is remote from the endthereof, thereby reducing the mechanical stresses to which the end wallof the central portion of the diaphragm is subjected.

[0015] In addition, because the end wall of the central portion of thediaphragm is subjected to less stress, it becomes easier to enable thediaphragm to perform its delivery valve function, i.e. to enable it toisolate the pump chamber from the opening(s) of the central duct whilethe volume of the pump chamber is increasing and substance is beingsucked into the chamber. The bottom portion of the central portion ofthe diaphragm can deform more easily in a direction perpendicular to thedirection in which the top portion of the central portion of thediaphragm is stretched because it is subjected to less axial stress, andthis makes it easier to pass the substance that is to be dispensed.

[0016] In a particular embodiment, the first engagement means of thediaphragm form a channel that is open in the direction facing away fromthe end wall of the central portion of the diaphragm, and the secondengagement means comprise an engagement skirt directed towards the endof the central duct.

[0017] Still in a particular embodiment, the above-mentioned channel isformed between two concentric tubular walls respectively constitutingthe bottom portion and the top portion of the central portion of thediaphragm, that overlap in part, and that are united by a transversewall constituting the web of said channel.

[0018] Advantageously, the tubular wall forming the bottom portion ofthe central portion of the diaphragm has at least one and preferably aplurality of axial slots in its radially inner surface.

[0019] These axial channels facilitate flow of the substance while it isbeing dispensed.

[0020] Advantageously, the above-mentioned axial slots extend downwardsfrom the top end of the tubular wall forming the bottom portion of thecentral portion of the diaphragm to perceptibly beneath theabove-mentioned transverse wall.

[0021] Advantageously, the diaphragm is arranged to isolate the pumpchamber from the opening(s) of the central duct by causing an annularregion to bear in leakproof manner against a zone of the central ductsituated beneath the second engagement means.

[0022] This zone of the central duct against which the diaphragm presseswhile the volume of the pump chamber is increasing and the substance isbeing sucked into the chamber is advantageously defined by an annularbead. The diaphragm co-operates with the central duct to provide annularclearance on either side of said bead, thereby making it easier for thesubstance to flow while it is being dispensed.

[0023] In a particular embodiment, the bottom portion of the centralduct has at least one radial opening.

[0024] In a variant, the bottom portion of the central duct does nothave any radial opening, which makes it easier to manufacture.

[0025] Advantageously, the second engagement means of the central ductare constituted by the ends of thicker portions of the central duct,said thicker portions leaving slots between one another enabling thesubstance to pass towards the opening(s) of the central duct.

[0026] Advantageously, the diaphragm has a flexible lip suitable firstlyfor isolating the pump chamber from the source of substance while thevolume of the pump chamber is decreasing, and secondly for enabling thesubstance to penetrate into the pump chamber while the volume thereof isincreasing.

[0027] This flexible lip acts somewhat like an intake valve.

[0028] Furthermore, the flexible lip is advantageously connected to thecentral portion of the diaphragm so as to form a downwardly open annularchannel, and the retaining means are constituted by the end of an innerskirt coming to bear against the web of said channel so as to retain thediaphragm when the moving member is moved downwards in order to decreasethe volume of the pump chamber.

[0029] The above-mentioned inner skirt advantageously has openings atits top end, the height of the openings being less than the height ofthe flexible lip, said openings enabling the substance to reach the pumpchamber while its volume is increasing, and while the flexible lip isspaced apart from the inner skirt under the effect of thrust from thesubstance flowing towards the pump chamber.

[0030] In a particular embodiment, the flexible lip is of thickness thatincreases going towards the top end of the diaphragm.

[0031] Still in a particular embodiment, the central portion of thediaphragm is connected at its top end to an annular portion of width andthickness selected in such a manner as to improve retention of thediaphragm while said central portion is being stretched.

[0032] Advantageously, the support includes sealing means bearing inleakproof manner against the tubular skirt of the moving member, saidtubular skirt being downwardly open and extending concentrically aroundthe central duct, said tubular skirt also defining the radially outerwall of the pump chamber.

[0033] Advantageously, when the pump is at rest, the portion of thediaphragm that extends axially between the retaining means and theengagement means of the duct is under tension, which enables the movingmember to be maintained in abutment in its high position.

[0034] The invention also provides a receptacle fitted with a pump asdefined above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other characteristics and advantages of the present inventionwill appear on reading the following detailed description ofnon-limiting embodiments and on examining the accompanying drawings, inwhich:

[0036]FIG. 1 is a fragmentary diagrammatic axial section view of areceptacle fitted with a pump constituting a first embodiment of theinvention;

[0037]FIG. 2 is an axial section view in a plane perpendicular to thatof FIG. 1;

[0038]FIG. 3 shows a detail of FIG. 1;

[0039]FIG. 4 shows the pushbutton in isolation;

[0040]FIG. 5 shows a detail of FIG. 4;

[0041]FIG. 6 is a perspective view in axial section showing thediaphragm in isolation;

[0042]FIG. 7 is a cross-section on line VII-VII of FIG. 4;

[0043]FIG. 8 is a view analogous to FIG. 1 showing a first variantembodiment of the pump;

[0044]FIG. 9 is an axial section in a plane perpendicular to that ofFIG. 8;

[0045]FIG. 10 shows a detail of FIG. 8;

[0046]FIG. 11 shows the pushbutton of the FIG. 8 pump in isolation:

[0047]FIG. 12 shows a detail of FIG. 11;

[0048]FIG. 13 is a view analogous to FIG. 1 showing a second variantembodiment of the pump;

[0049]FIG. 14 is an axial section in a plane perpendicular to that ofFIG. 13;

[0050]FIG. 15 shows a detail of FIG. 13; and

[0051]FIG. 16 shows the pushbutton of the FIG. 13 pump in isolation.

MORE DETAILED DESCRIPTION

[0052]FIG. 1 shows a receptacle 1 having a tank-forming body 2, and thedrawing shows only the top end thereof which defines a neck 3 onto whicha support 4 is snap-fastened.

[0053] The support 4 constitutes a guide for mounting a pushbutton 5 toslide along an axis X, and it also serves to mount a removable closurecap 6 that covers the pushbutton 5 before first use thereof.

[0054] In the embodiment described, the support 4 has a sealing skirt 7bearing in leakproof manner against the inside surface of the neck 3.

[0055] The sealing skirt 7 is extended radially firstly outwards byfixing tabs 8 that are snap-fastened on an annular rim 9 of the neck 3,and secondly inwards by a stepped wall 10 defining an endpiece 12 forconnection to a dip tube (not shown).

[0056] An outer skirt 15 and a guide skirt 16 are made as a one-piecemolding of plastics material together with the sealing skirt 7, thefixing tabs 8, and the stepped wall 10.

[0057] The outer skirt 15 extends around the neck 3 of the receptacleand has a shoulder 17 against which the closure cap 6 bears.

[0058] The top edge 18 of the outer skirt 15 retains the pushbutton 5 atrest, as described below.

[0059] The support 4 has an inner skirt 20 constituted by an insertwhose bottom end 21 is engaged by force in the stepped wall 10.

[0060] The inner skirt 20 has a perceptibly tapering top end providedwith radial openings 22 as can be seen more particularly in FIG. 3.

[0061] These openings 22 in the example described are in the form ofslots running parallel to the axis X, and extended downwards by grooves25 extending along the radially inner surface of the inner skirt 20 asfar as a step 26.

[0062] A pair of annular sealing lips 24 are made integrally with theinner skirt 20 on the outside thereof by molding a plastics material.

[0063] The pushbutton 5 has an outer skirt 30 provided at its bottom endwith catches 31 that come into abutment against the top edge 18 of theouter skirt 15 of the support 4 when the pushbutton 5 is at rest in itshigh position, as shown in FIG. 1.

[0064] The pushbutton 5 also has a central duct 32 on the axis X and aconcentric tubular skirt 33 defining an annular pump chamber 34 aroundthe central duct 32.

[0065] The outer skirt 30, the tubular skirt 33, and the central duct 32are made integrally by molding a plastics material together with adispensing endpiece 35 that communicates internally with the centralduct 32.

[0066] In the embodiment shown in FIGS. 1 to 3, the bottom end 87 of thecentral duct 32 has radial openings 36.

[0067] The bottom end of the tubular skirt 33 forms a sealing lip 37extending radially outwards a little.

[0068] The guide skirt 16 of the support 4 has a circularly cylindricalinside surface 40 in its top portion and a shallow annular setback 41 inits bottom portion.

[0069] When the pushbutton 5 is in the high position, the sealing lip 37bears in leakproof manner against the inside surface 40 of the topportion of the guide skirt 16, as shown in FIG. 1.

[0070] The inside of the receptacle is thus isolated from thesurrounding air, which favors good conservation of the substance.

[0071] When the pushbutton 5 is pressed down, the sealing lip 37 ceasesto bear in leakproof manner against the guide skirt 16 because of theannular setback 41, thereby enabling the annular channel formed betweenthe inner skirt 20 and the guide skirt 16 to communicate with theoutside via the annular clearance 42 shown in FIG. 3.

[0072] The inner skirt 20 serves to mount a diaphragm 50 which is shownin isolation in FIG. 6, the diaphragm having a sleeve-forming centralportion 51 on the axis X which is open at its top end and closed at itsbottom end by an end wall 52.

[0073] The diaphragm 50 is made of a silicone or nitrile elastomer andit has a downwardly directed flexible annular lip 53 extending from itstop.

[0074] Where it connects with the central portion 51, the flexible lip53 forms a downwardly open annular channel 54 in which the top end ofthe inner skirt 20 is inserted until its free edge in said channel 54bears against the web 55 connecting the flexible lip 53 to the centralportion 51.

[0075] The flexible lip 53 is made so as to bear lightly against theinner skirt 20 when at rest.

[0076] The height of the flexible lip 53 is greater than that of theopenings 22 and, at rest, the flexible lip 53 is suitable for bearing inleakproof manner against the outer surface of the inner skirt 20 belowthe openings 22, as shown in FIG. 1.

[0077] The flexible lip 53 thus acts as an intake valve, isolating thepump chamber 34 from the inside of the receptacle while the volume ofthe pump chamber is decreasing to dispense a quantity of substance, asdescribed below.

[0078] The wall 55 connecting the flexible lip 53 to the central portion51 is relatively broad and thick, thus enabling it to hold the top endof the central portion 51 of the diaphragm securely relative to theinner skirt 20 when the pushbutton 5 is pressed down.

[0079] The central duct 32 has axially-extending thicker portions 60 onits outside surface, there being three such portions in the embodimentdescribed, and these portions leave axial slots 61 between them, as canbe seen in FIG. 7.

[0080] The slots 61 extend along the major portion of the height of thecentral duct 32 from its top end and along the entire length of thethicker portions 60.

[0081] At their bottom ends the thicker portions form an engagementskirt 64 which co-operates with the central duct 32 to form a downwardlyopen annular channel 65.

[0082] In the embodiment described, the engagement skirt 64 is situatedbetween one-fourth and one-third of the total height of the central duct32 from its bottom end 87.

[0083] The central portion 51 of the diaphragm 50 has a top portion 56and a bottom portion 57.

[0084] The bottom portion is connected to the top portion 56 via atransverse wall 58 extending radially inwards from the bottom end of thetop portion 56.

[0085] The bottom portion 57 extends over the transverse wall 58 insidethe top portion 56 so as to form an engagement skirt 59 whichco-operates with the top portion 56 to form an upwardly open annularchannel 70.

[0086] When the diaphragm 50 is in place on the support 4, theengagement skirt 64 of the central duct 32 is received in the channel 70and the engagement skirt 59 of the diaphragm 50 is received in thechannel 65 such that when the pushbutton 5 is pressed down, the centralportion 51 of the diaphragm is pulled downwards essentially byengagement of the diaphragm on the engagement skirt 64 of the centralduct 32.

[0087] The thickness of the engagement skirt 54 correspondssubstantially to the width of the annular channel 70.

[0088] Axial slots 72 are formed in the inside face of the bottomportion 57 of the central portion 51 of the diaphragm, as can be seen inFIG. 6.

[0089] These slots 72 are of a depth which decreases progressively oncoming towards the end wall 52 of the diaphragm, as can be seen in FIG.3.

[0090] In the embodiment described, the slots 72 open out to the top endof the bottom portion 57 of the diaphragm.

[0091] The annular region 75 of the bottom portion 57 of the diaphragmwhich extends axially between the bottom ends of the slots 72 and theend wall 52 extends over a height that is greater than that of theradial openings 36 in the central duct 32.

[0092] In addition, in the embodiment described, the inside diameter ofsaid annular region 75 is selected in such a manner that at rest itbears in leakproof manner against the central duct 32 above the radialopenings 36, thereby isolating them from the slots 72.

[0093] The pump 1 operates as follows.

[0094] It is assumed that the pump 1 is primed.

[0095] When the user pushes the pushbutton 5 down, the central duct 32moves downwards and the top portion 56 of the diaphragm is stretchedelastically, being retained at its top end by the top end of the innerskirt 20 and being engaged at its bottom end on the engagement skirt 64.

[0096] The substance contained in the pump chamber 34 is compressed andthe flexible lip 53 bears in leakproof manner against the outside faceof the inner skirt 20.

[0097] Under the pressure of the substance, the annular region 75 of thediaphragm 50 moves away from the central duct 32 and the substance canreach the radial openings 36 so as to flow via the inside of the centralduct to the outlet orifice of the dispensing endpiece 35.

[0098] Because the diaphragm 50 is engaged on the central duct 32 at alocation that is remote from the end wall 52, the end wall is subjectedto little mechanical stress while substance is being dispensed, and theannular region 75 which is not stretched to any great extent can moveaway from the central duct 32 relatively easily under the pressure ofthe substance which flows via the slots 61.

[0099] When the user releases the pushbutton 5, the top portion 56 ofthe diaphragm 50 returns under its own elasticity to its initial shape,thereby returning the pushbutton 5 upwards.

[0100] Suction is then established in the pump chamber 34 which has theeffect of moving the flexible lip 53 away from the inner skirt 20 andallowing substance to reach the pump chamber 34 by flowing inside theendpiece 12 and the grooves 25 made in the inside face of the innerskirt 20.

[0101] The suction which is established in the pump chamber 34 while thepushbutton 5 is rising also has the effect of pressing the annularregion 75 of the diaphragm against the central duct 32 and thus ofisolating the radial openings 36 from the pump chamber 34.

[0102] In the pump of the invention, the spring function of thediaphragm is somewhat independent from its delivery valve function,because the diaphragm is engaged on the central duct at a location whichis remote from the bottom end of the diaphragm.

[0103] In other words, between the two regions where the diaphragm isengaged on the support and on the central duct respectively, thediaphragm has no function other than a spring function and it does notperform a valve function.

[0104] To assemble the pump 1, the diaphragm 50 is initially put intoplace on the central duct 32 of the pushbutton 5 and then the pushbuttonis put into place on the support 4, with the catches 31 deformingelastically to move past the top edge 18 of the outer skirt 15.

[0105] The length of the top portion 56 of the diaphragm 50 is selectedin such a manner that when the pushbutton 5 comes to bear via itscatches 31 against said top edge 18, the diaphragm is under tension.

[0106] FIGS. 8 to 12 show a variant embodiment.

[0107] In these figures, the same reference symbols are used forelements that are identical to those described above.

[0108] The pump 1′ shown in FIGS. 8 to 12 differs from that describedabove by the shape of the central duct 32′ of the pushbutton 5′ and bythe shape of the diaphragm 50′.

[0109] More precisely, the central duct 32′ in this variant embodimenthas a radial opening 36′ of smaller height, and it has an annular bead80 at a relatively short distance from its bottom end 87 and above theradial opening 36′.

[0110] Otherwise the central duct 32′ is identical to the central duct32 as described above.

[0111] The diaphragm 50′ has a central portion 51′ whose bottom portion57′ has an inside diameter that is slightly greater than that of thebottom portion 81 of the central duct 32′, and co-operates therewith toleave annular clearance 82, as can be seen in FIG. 10.

[0112] The inside diameter of the bottom portion 57′ corresponds to theoutside diameter of the annular bead 80 so that the bottom portion 57′at rest presses against said annular bead 80 in leakproof manner.

[0113] Axial slots 72′ are formed in the inside face of the bottomportion 57′.

[0114] These slots 72′ open out at their bottom ends in the annularclearance 82 above the bead 80.

[0115] The diaphragm 50′ is otherwise identical to the diaphragm 50 asdescribed above.

[0116] In the embodiment of FIGS. 8 to 12, flow of the substance whilethe pushbutton 5′ is being pushed down is made easier by the presence ofthe annular clearance 82.

[0117] FIGS. 13 to 16 show a pump 1″ constituting a second variantembodiment of the invention.

[0118] This pump 1″ differs from the pump shown in FIG. 1 by the factthat the central duct 32″ of the pushbutton 5″ does not have radialopenings 36, but merely the axial opening 86 defined by the circularedge at the bottom end 87 of the central duct 32″.

[0119] In spite of that, the pump 1″ can operate properly because theend wall 52 of the diaphragm 50 which is of substantially the samethickness as the annular region 75 is capable of deforming downwardsunder drive from the pressure of the substance when the pushbutton 5″ ispushed down, since the end wall 52 is not under tension due to the factthat the diaphragm 50 is engaged to the engagement skirt 64 at a pointthat is higher up.

[0120] Naturally, the invention it not limited to the embodimentsdescribed above.

[0121] In particular, it is possible to modify the shape of thediaphragm, that of the engagement means for engaging the diaphragm onthe central duct, and indeed the shape of the support and of thepushbutton without thereby going beyond the ambit of the presentinvention.

1. A pump of the type comprising a moving member mounted to moverelative to a support, the moving member having a central duct in whichthe substance to be dispensed penetrates via at least one opening, thesupport cooperating with the moving member to define a variable-volumepump chamber around said central duct, the pump having a diaphragm heldby retaining means on the support, the diaphragm having a centralportion in which one end of said central duct is inserted, the diaphragmhaving a valve-forming portion arranged to isolate the pump chamber fromsaid opening(s) of the central duct while the volume of the pump chamberis increasing and the substance is being sucked into the pump chamber,the diaphragm also bearing against the moving member in such a mannerthat movement of the moving member to dispense the substance causes thediaphragm to be stretched elastically, the pump having means suitable,during movement of the moving member for dispensing the substance, forminimizing the stretching of the valve-forming portion of saiddiaphragm.
 2. A pump according to claim 1 , wherein the diaphragm hasfirst engagement means arranged to co-operate with second engagementmeans secured to said central duct, said second engagement means beingspaced apart from the end of the central duct.
 3. A pump according toclaim 1 , wherein the portion of the diaphragm extending between theretaining means of the support and the engagement zone of the centralduct performs a spring function only.
 4. A pump according to claim 3 ,wherein the portion of the valve-forming diaphragm that is arranged toisolate the pump chamber from the opening(s) of the central duct liesoutside the portion of the diaphragm that extends between the zone forfixing on the support and the zone for engagement on the central duct.5. A pump according to claim 1 , wherein the first engagement means ofthe diaphragm form a channel that is open in the direction facing awayfrom the end wall of the central portion of the diaphragm, and thesecond engagement means comprise an engagement skirt directed towardsthe end of the central duct.
 6. A pump according to claim 5 , whereinthe channel is formed between two concentric tubular walls respectivelyconstituting the bottom portion and the top portion of the centralportion of the diaphragm, that overlap in part, and that are united by atransverse wall constituting the web of said channel.
 7. A pumpaccording to claim 6 , wherein the tubular wall forming the bottomportion of the central portion of the diaphragm has at least one andpreferably a plurality of axial slots in its radially inner surface. 8.A pump according to claim 7 , wherein said axial slots extend downwardsfrom the top end of the tubular wall forming the bottom portion of thecentral portion of the diaphragm to perceptibly beneath the transversewall.
 9. A pump according to claim 1 , wherein the diaphragm is arrangedto isolate the pump chamber from the opening(s) of the central duct bycausing an annular region to bear in leakproof manner against a zone ofthe central duct situated beneath the second engagement means.
 10. Apump according to claim 9 , wherein the zone of the central duct againstwhich the diaphragm bears while the volume of the pump chamber isincreasing and the substance is being sucked into the pump chamber isdefined by an annular bead.
 11. A pump according to claim 10 , whereinthe diaphragm co-operates with the central duct to provide annularclearance on either side of said bead.
 12. A pump according to claim 1 ,wherein the bottom portion of the central duct has at least one radialopening.
 13. A pump according to claim 1 , wherein the bottom portion ofthe central duct does not have any radial opening.
 14. A pump accordingto claim 1 , wherein the second engagement means of the central duct areconstituted by the ends of thicker portions of the central duct, saidthicker portions leaving slots between one another enabling thesubstance to pass towards the opening(s) of the central duct.
 15. A pumpaccording to claim 1 , wherein the diaphragm has a flexible lip suitablefirstly for isolating the pump chamber from the source of substancewhile the volume of the pump chamber is decreasing, and secondly forenabling the substance to penetrate into the pump chamber while thevolume thereof is increasing.
 16. A pump according to claim 15 , whereinthe flexible lip is connected to the central portion of the diaphragm soas to form a downwardly open annular channel, and wherein the retainingmeans are constituted by the end of an inner skirt coming to bearagainst the web of said channel so as to retain the diaphragm when themoving member is moved downwards in order to decrease the volume of thepump chamber.
 17. A pump according to claim 16 , wherein the inner skirthas openings at its top end, the height of the openings being less thanthe height of the flexible lip, said openings enabling the substance toreach the pump chamber while its volume is increasing, and while theflexible lip is spaced apart from the inner skirt under the effect ofthrust from the substance flowing towards the pump chamber.
 18. A pumpaccording to claim 15 , wherein the flexible lip is of thickness thatincreases going towards the top end of the diaphragm.
 19. A pumpaccording to claim 15 , wherein the central portion of the diaphragm isconnected at its top end to an annular portion of width and thicknessselected in such a manner as to improve retention of the diaphragm whilesaid central portion is being stretched.
 20. A pump according to claim 1, wherein the support includes sealing means bearing in leakproof manneragainst the tubular skirt of the moving member, said tubular skirt beingdownwardly open and extending concentrically around the central duct,said tubular skirt also defining the radially outer wall of the pumpchamber.
 21. A pump according to claim 1 , wherein, when the pump is atrest, the portion of the diaphragm that extends axially between theretaining means and the engagement means of the duct is under tension.22. A pump according to claim 1 , wherein the moving member constitutesthe pushbutton, the central duct being integrally formed with adispensing endpiece.
 23. A pump according to claim 1 , wherein thediaphragm is made of a nitrile elastomer or a silicon elastomer.
 24. Areceptacle fitted with a pump as defined in claim 1 .